1. Field of the Invention
The invention relates to a sleep system, and particularly it relates to a sleep system that stimulates a target person.
2. Description of Related Art
A system has been proposed which is capable of maintaining the sleep depth of a driver, as a user, at a constant level. For example, Japanese Patent Application Publication No. 2009-213711 describes a sleep system that is provided with: a sleep depth determination portion that determines the present sleep depth of the driver; a sleep depth comparison portion that compares, the present sleep depth, determined by the sleep depth determination portion, with a target sleep depth that is a predetermined sleep depth smaller than the maximum sleep depth; and a stimulation control portion and a stimulation device that are used to apply to the user a sensory threshold stimulus of a level based on a human body sensory threshold, when the sleep depth comparison portion determines that the present sleep depth has reached the target sleep depth.
However, for example, when the present sleep depth is very large, the sleep depth may not be properly controlled through a stimulus based on a sensory threshold.